The renin-angiotensin-aldosterone system, or RAAS, is a peptidergic cascade with angiotensin II as its key effector. In healthy physiology it regulates blood pressure and fluid balance. In heart failure, reduced cardiac output, arterial underfilling and direct renal sympathetic stimulation push the system into overdrive, and the consequences are destructive: vasoconstriction, oxidative stress, inflammation, fibrosis of the heart and vasculature, and amplification of sympathetic nervous activity. Blocking this cascade with ACE inhibitors, angiotensin receptor blockers, angiotensin receptor-neprilysin inhibitors and mineralocorticoid receptor antagonists is a cornerstone of modern heart failure therapy. Yet guidelines do not routinely recommend these drugs after heart transplantation, and the question of whether the hormonal storm actually resolves once hemodynamics are corrected has remained largely unanswered.

To find out, the Vienna team enrolled patients with end-stage heart failure who were undergoing either heart transplantation or implantation of a left ventricular assist device, or LVAD, into a prospective registry. In total, 49 transplant recipients and 12 LVAD recipients were followed, with blood sampling shortly before and approximately six months after the intervention. The investigators measured NT-proBNP, the widely used marker of cardiac stress, plasma active renin concentration, aldosterone, and crucially the complete profile of circulating angiotensin peptides. Blood was drawn into tubes containing an inhibitor cocktail that instantly freezes angiotensin metabolism, allowing the researchers to capture a faithful snapshot, or fingerprint, of the circulating RAS at the moment of sampling.

The fingerprinting technique itself is a technical tour de force. Plasma samples were spiked with stable isotope-labeled internal standards for ten different angiotensin metabolites, then analyzed by liquid chromatography tandem mass spectrometry after solid-phase extraction. Because renin-dependent generation of angiotensin I is the rate-limiting step of the cascade, and ACE converts angiotensin I into angiotensin II, the relative abundance of downstream peptides such as angiotensin 1-7, angiotensin 1-5, angiotensin III and angiotensin IV reveals both the magnitude of systemic RAS activation and the mode of any pharmacological blockade. The sum of angiotensin I and angiotensin II served as a measure of the angiotensin burden carried by the classical RAS axis.

The results were unambiguous. After heart transplantation, the use of RAS inhibitors dropped significantly, as beta-blocker use fell from 63 to 2 percent and mineralocorticoid antagonist use collapsed from 55 to 8 percent, reflecting the standard de-escalation of heart failure drugs after transplant. In LVAD patients, by contrast, neurohormonal therapy remained broadly comparable before and after implantation, consistent with the strategy of continuing medication to promote reverse remodeling and myocardial recovery. Both interventions produced marked improvements in the visible signs of neurohumoral dysregulation. NT-proBNP fell from a median of 3015 to 1140 pg/mL after transplantation and from 8980 to 1836 pg/mL after LVAD implantation, while active renin concentration declined from 278 to 87 µIU/mL and from 847 to 131 µIU/mL respectively.

But the improvement stopped well short of normal. Not a single patient achieved normal NT-proBNP values after either intervention, and only 24 percent of transplant recipients and 33 percent of LVAD recipients reached normal renin levels. Plasma renin remained elevated in 76 percent of heart transplant patients and 67 percent of LVAD recipients, and in those patients clearly measurable angiotensin II persisted in the circulation. The angiotensin burden of the classical axis fell substantially after transplantation, from a median of 159 to 47 ng/L, and dropped numerically in the LVAD group from 214 to 42 ng/L, but it did not vanish. Aldosterone concentrations, notably, showed no significant change after either procedure. A tight correlation between renin and the combined angiotensin I plus angiotensin II levels, with a Spearman coefficient of 0.87, confirmed that renin remains the rate-limiting driver of the circulating cascade even after hemodynamic rescue.

Why does the hormonal system refuse to reset? The authors suggest a combination of mechanisms. In transplant recipients, persistent natriuretic peptide elevation has been attributed to cardiac denervation, immunosuppressive therapy, ventriculo-vascular uncoupling, endothelial dysfunction and subclinical allograft rejection. Prior studies have shown that natriuretic peptide levels peak within months of transplantation and decline gradually, but rarely normalize even years later; importantly, a late rise in NT-proBNP correlates strongly with allograft rejection, making these biomarkers clinically meaningful rather than mere curiosities. In LVAD patients, the picture is complicated by the devices themselves. Continuous-flow pumps may fail to stimulate arterial baroreceptors the way pulsatile flow does, potentially desensitizing receptors and raising intrinsic sympathetic tone, which in turn drives RAAS activation. Non-pulsatile kidney perfusion may independently activate the system, and preclinical work has linked continuous flow to impaired endothelial function, renal cortical artery hypertrophy and inflammatory infiltration.

The clinical implications are considerable. Ongoing angiotensin II spill-over is not a benign biochemical footnote: the peptide promotes the very processes, remodeling, fibrosis, inflammation and vascular dysfunction, that produce complications such as right ventricular failure in LVAD patients and possibly graft injury in transplant recipients. The study’s findings support a rationale for cardioprotective treatment, particularly with RAS inhibitors, in most patients after both transplantation and LVAD implantation, even though current transplant guidelines do not routinely recommend these agents. The Vienna group cautions, however, that this remains a hypothesis in this population. The impact of RAS inhibition specifically after transplantation and mechanical support should be tested in dedicated studies, and the long-term consequences of such a strategy, including interactions with immunosuppression and renal function, need careful evaluation.

Beyond its immediate therapeutic message, the study offers a conceptual shift. It reframes advanced heart failure not simply as a pumping problem that surgery can fix, but as a systemic neurohormonal disease whose imprint survives the replacement of the organ that caused it. The angiotensin fingerprints captured by mass spectrometry provide a new window into individual RAS regulation, showing exactly how pharmacological blockade reshapes the peptide landscape and where activation persists. For the growing population of patients living with transplanted hearts or mechanical circulatory support, the message is that the endocrine apparatus retains a memory of the failure it once served, and that memory may be a modifiable target for improving long-term outcomes.

Subject of Research: Persistent renin-angiotensin system activation and neurohormonal memory after heart transplantation or LVAD implantation in end-stage heart failure patients

Article Title: Memory of the renin-angiotensin system following heart transplantation or implantation of a left ventricular assist device

Article References: Memory of the renin-angiotensin system following heart transplantation or implantation of a left ventricular assist device. (n.d.). https://doi.org/10.1007/s00392-026-03018-x

Image Credits: AI Generated

DOI: 10.1007/s00392-026-03018-x

Keywords: heart failure, heart transplantation, LVAD, renin-angiotensin system, angiotensin II, NT-proBNP, neurohormonal activation, mass spectrometry, cardiac remodeling, RAS inhibitors, aldosterone, plasma renin

The single most transformative technical development of the period is widely agreed to be the sequencing revolution. The landmark 2005 demonstration of genome sequencing in microfabricated high-density picolitre reactors opened the door to reading tumour genomes at scale, an advance that would have been unimaginable when the journal launched. From that technological foundation flowed the systematic discovery of cancer genes, the classification of tumours by their mutational signatures and the rise of precision oncology as a clinical discipline. The identification of recurrent mutations of the BRAF gene in human cancer in 2002, before the sequencing revolution fully matured, had already signalled what was to come: single genetic lesions, once found, could define entire treatment strategies.

Clinical actionability has expanded at a remarkable pace. Analyses quantifying the expanding landscape of clinical actionability for patients with cancer show that a steadily growing fraction of tumours now harbour alterations for which targeted drugs or guided treatment decisions exist. The poster child of this era remains BRAF V600E inhibition in melanoma, but the paradigm has matured in sophistication. When colon cancers proved unexpectedly unresponsive to BRAF inhibition, researchers discovered that feedback activation of EGFR was protecting the cells—a finding that led directly to the FDA-approved combination of BRAF and EGFR inhibitors for BRAF-mutant colorectal cancer, a therapy developed in René Bernards’ laboratory at the Netherlands Cancer Institute. The lesson embedded in that story reshaped the field: cancers are wired for resilience, and single-agent thinking is rarely sufficient.

That lesson now drives the logic of synthetic lethality, one of the most productive conceptual frameworks of the past decade. Rather than attacking oncogenes directly, synthetic lethal strategies exploit vulnerabilities created by a tumour’s alterations. A striking recent example is the demonstration that amplification of the cyclin E1 gene CCNE1, common in aggressive ovarian and other cancers, creates a dependence on the PKMYT1 kinase that can be pharmacologically exploited. This approach extends druggability into territory long considered untouchable, and drug discovery scientist Paul Workman of the Institute of Cancer Research has championed the broader project of drugging the cancer genome—developing chemical inhibitors and small-molecule research tools against targets once dismissed as intractable.

Perhaps no target symbolises both the promise and the frustration of the era better than RAS. Mutant RAS genes were identified in the early 1980s and were long considered undruggable, a verdict repeated in reviews for decades. Yet the past few years have delivered direct RAS inhibitors, and a 2026 phase three trial reported that the RAS inhibitor daraxonrasib outperformed chemotherapy in previously treated metastatic pancreatic cancer—one of the most difficult malignancies to treat. Allan Balmain, whose laboratory uses mouse models to trace the cells that acquire initiating oncogenic mutations, notes that interpreting such advances requires a deeper understanding of tumour evolution itself: when a mutation arises, in which cell it arises, and what environmental forces promote or suppress its expansion.

That evolutionary perspective has been genuinely subversive. Sequencing of normal human skin revealed a high burden of somatic mutations and pervasive positive selection operating in histologically normal tissue—mutant clones competing for space in organs that look entirely healthy. Even more provocative, work in mosaic mouse skin has shown that injury can prevent the expansion of Ras-mutant cells, overturning the intuitive assumption that wounding uniformly promotes carcinogenesis. Complementing this, chemically induced skin tumours have been traced to long-lived stem cells of the upper hair follicle, underscoring that the identity of the cell of origin is a decisive variable in tumour outcome. Cancer, in this view, is not simply a cell-autonomous genetic disease but an ecological process embedded in tissue dynamics, environmental exposure and time.

The cancer stem cell concept illustrates how an important idea can be discovered, oversimplified and then properly understood only over decades. The founding observation—that human acute myeloid leukemia is organized as a hierarchy originating from a primitive hematopoietic cell—was published in 1997, before the review period began. The intervening years saw the concept generalized, contested and eventually refined. As Hans Clevers and Eduard Batlle argued in revisiting the field, functional stemness depends on cellular context and state rather than immutable identity, and epithelial cell plasticity allows cells to cross lineage boundaries that once seemed fixed. The modern synthesis holds that many tumour cells can transiently adopt stem-like behaviour, which has important consequences for therapy resistance and relapse, even if the simplest hierarchical models proved too rigid.

Technology has also reshaped how tumours are studied. Clevers’ pioneering work on organoids—self-organizing, three-dimensional cultures derived from adult stem cells—created patient-derived models that preserve the genetic and functional features of the original tissue, bridging the long-standing gap between cell lines and patients. Organoid biobanks now support drug screening, gene-function studies and personalised treatment predictions, and the technology has been commercialised widely, with Clevers holding patents and co-founding companies in the field. Alongside organoids, powerful tools such as CRISPR-based functional genomics, exemplified by the synthetic lethality screens of the Bernards laboratory, allow systematic interrogation of cancer vulnerabilities directly in human cells.

Beyond genes, the anniversary reflections give substantial weight to metabolism and the tumour microenvironment, areas that were marginal when the journal began but are now central. Tumour-derived lactic acid was shown to functionally polarise tumour-associated macrophages, demonstrating that a metabolic by-product can reprogram immune cells within the microenvironment. Cancer-associated cachexia, the devastating wasting syndrome that contributes to a large fraction of cancer deaths, has recently been connected to mechanistic insight in human studies, replacing decades of descriptive work. Karen H. Vousden, whose research spans p53 biology and metabolism, has explored how dietary composition interacts with tumour metabolism, and precision nutrition companies are now testing whether manipulating non-essential amino acids can enhance therapy in patients. The message is that cancer cannot be understood as a tumour in isolation; it is a systemic disease reshaping the entire body.

The newest force transforming the field is artificial intelligence. The transformer architecture described in ‘Attention is all you need’ underpins models that now predict biomolecular interactions with remarkable accuracy, as demonstrated by AlphaFold 3, and AI agents are being designed to empower biomedical discovery end to end—from hypothesis generation to experimental execution. Marinka Zitnik of Harvard Medical School leads work on multimodal and agentic AI systems paired directly with laboratory experiments, and is team lead of AURORA within Cancer Grand Challenges. The authors’ cautious optimism is tempered by experience: past waves of overhyped technologies promised more than they delivered, and AI will need to demonstrate genuine predictive power in clinics, not only impressive benchmarks, to transform outcomes.

Woven through the reflections is an honest accounting of unmet expectations. Not every large-scale endeavour—from indiscriminate high-throughput screening to simplistic gene-expression signatures—delivered what early enthusiasts forecast. Combination therapy remains difficult to develop because toxicity, not efficacy, is usually the limiting factor. Drug resistance evolves faster than new drugs arrive, and late-stage solid tumours continue to claim most of the lives that cancer kills. Yet the trajectory is unmistakable: five-year survival has risen for many malignancies, targeted combinations have turned once-fatal diseases into chronic or curable conditions, and the mechanistic depth of the field is unrecognisable compared with 2001. The authors’ shared conclusion is that the next 25 years will be judged by how well the field integrates these hard-won insights—evolutionary, ecological, metabolic and computational—into treatments that reach every patient, not just those with actionable mutations in privileged tumour types.

Subject of Research: A 25-year retrospective on transformative advances and unmet expectations in cancer research

Article Title: Reflecting on 25 years of cancer research: transformative advances and unmet expectations

Article References: Balmain, A., Bernards, R., Clevers, H., Vousden, K. H., Workman, P., & Zitnik, M. (2026). Reflecting on 25 years of cancer research: transformative advances and unmet expectations. Nature Reviews Cancer. https://doi.org/10.1038/s41568-026-00974-4

Image Credits: AI Generated

DOI: 10.1038/s41568-026-00974-4

Keywords: cancer research, Nature Reviews Cancer, tumour evolution, precision oncology, synthetic lethality, RAS inhibitors, cancer stem cells, organoids, tumour metabolism, cachexia, artificial intelligence, drug discovery